The present invention relates generally to a glenoid component, and more particularly to an augmented glenoid component and associated method for securing the augmented glenoid component to a glenoid surface of a scapula.
During the lifetime of a patient, it may be necessary to perform a total shoulder replacement procedure on the patient as a result of, for example, disease or trauma. In a total shoulder replacement procedure, a humeral component having a head portion is utilized to replace the natural head portion of the arm bone or humerus. The humeral component typically has an elongated intramedullary stem which is utilized to secure the humeral component to the patient""s humerus. In such a total shoulder replacement procedure, the natural glenoid surface of the scapula is resurfaced or otherwise replaced with a glenoid component that provides a bearing surface for the head portion of the humeral component.
As alluded to above, the need for a shoulder replacement procedure may be created by the presence of any one of a number of conditions. One such condition is the deterioration of the patient""s scapula in the area proximate to the glenoid surface as a result of, for example, glenohumeral arthritis. In such a condition, the erosion of the patient""s scapula is generally observed posteriorly on the glenoid surface. Such erosion of the scapula renders treatment difficult, if not impossible, with a conventional glenoid prosthesis.
In order to treat a condition in which a portion of the scapula has been eroded, a number of glenoid prostheses have heretofore been designed. Such glenoid prostheses, known generally as augmented glenoid prostheses, have a posterior edge that is thicker than the corresponding anterior edge. In FIG. 1A, a heretofore-designed augmented glenoid component 100 is shown. The glenoid component 100 has a metallic backing component 102 and plastic insert 104. The thickness of the metallic backing component 102 gradually increases from an anterior edge 106 to a posterior edge 108 thereof thereby creating a relatively smooth, arcuate-shaped medial surface 110 from which a number of posts or pegs 112 extend.
The design of the augmented glenoid component 100, however, has a number of associated drawbacks. For example, the relatively smooth, arcuate-shaped medial surface 110 may over time lead to loosening of the augmented glenoid component 100, thereby potentially necessitating additional surgical procedures to replace or reseat the component 100. Further, due to the configuration of the medial surface 110, a relatively high shear load is created along the implant-to-bone interface when the component 100 is implanted. The presence of a high shear load along the implant-to-bone interface tends to also cause loosening of the component 100 over a period of time. Post-operative loosening is the largest cause of failures of implanted glenoid components.
In FIG. 1B another heretofore-designed augmented glenoid component 100a is shown. The glenoid component 100a has a single component plastic body 102a. The thickness of the plastic body 102a gradually increases from an anterior edge 106a to a posterior edge 108a thereof thereby creating a relatively smooth, arcuate-shaped medial surface 110a from which a number of posts or pegs 112a extend. The design of this augmented glenoid component 100a, however, suffers from at least the same drawbacks as the glenoid component 100.
In FIG. 1C another heretofore-designed augmented glenoid component 100b is shown. The glenoid component 100b also has a single component plastic body 102b. The thickness of the plastic body 102b gradually increases from an anterior edge 106b to a posterior edge 108b thereof thereby creating a relatively smooth medial surface 110b from which a keel 114 extends. The design of this augmented glenoid component 100b, however, suffers from at least the same drawbacks as the glenoid components 100 and 100a. 
What is needed therefore is an augmented glenoid component that overcomes one or more of the above-mentioned drawbacks. What is further needed is an augmented glenoid component that is less susceptible to postoperative loosening relative to heretofore designed glenoid components.
The subject invention is a glenoid component and associated method for securement thereof to a glenoid surface of a scapula. Particularly, the subject invention is an augmented glenoid component and associated method for securement thereof to a glenoid surface of a scapula. More particularly, the subject invention is an augmented glenoid component having an interruption or the like and an associated method for securement of the augmented glenoid component to a glenoid surface of a scapula.
In one form, the interruption is defined by a buttress, step, shoulder, ledge, interface or the like that extends from a surface of a component body that defines at least a portion of the present augmented glenoid component. The body may also include anchoring. In one form, the anchoring of the body may comprise one or more anchors. An anchor may extend entirely from the surface of the body, entirely from the interruption, or from both the interruption and the surface (i.e. straddling).
In accordance with an embodiment of the subject invention, there is provided an augmented glenoid component for securement to a glenoid surface of a scapula so as to provide a bearing surface for a head portion of a humerus. The augmented glenoid component includes a body and a buttress. The body has a first body surface configured to contact the glenoid surface of the scapula, and a second body surface configured to be contacted by the head portion of the humerus. The buttress is formed in the first body surface of the body.
In accordance with another embodiment of the subject invention, there is provided an augmented glenoid component for securement to a glenoid surface of a scapula so as to provide a bearing surface for a head portion of a humerus. The augmented glenoid component includes a body, medial surface on the body, a humerus surface on the body, an interruption, and anchoring. The medial surface is configured to contact the glenoid surface of the scapula. The humerus surface is configured to be contacted by the head portion of the humerus. The interruption extends from the medial surface and defines a first interruption surface positioned relative to the medial surface at an angle xcex8 in which 45xc2x0xe2x89xa6xcex8xe2x89xa6135xc2x0, and a second interruption surface positioned relative to a line parallel to the first body surface an angle xcfx86 in which 0xc2x0xe2x89xa6xcfx86xe2x89xa690xc2x0.
In accordance with a further embodiment of the subject invention, there is provided a method of securing an augmented glenoid component to a glenoid surface of a scapula so as to provide a bearing surface for a head portion of a humerus. The augmented glenoid component has: (i) a body having: (a) a first body surface configured to contact the glenoid surface of the scapula, and (b) a second body surface configured to be contacted by the head portion of the humerus; and (ii) a buttress extending from the first body surface. The method includes the steps of (a) forming a buttress-shaped recess in the glenoid surface of the scapula; and (b) securing the augmented glenoid component to the glenoid surface of the scapula such that: (i) the first body surface is positioned in contact with the glenoid surface of the scapula, and (ii) the buttress is positioned in the step-shaped recess.
In all embodiments, the present augmented glenoid component provides good stabilization after implant. Further, the present augmented glenoid component converts normal high shear loads into compressive loading thereby reducing stress on the glenoid component. The present augmented glenoid component may be used to correct bone defects or wear.
It is therefore an object of the subject invention to provide a new and useful augmented glenoid component.
It is moreover an object of the subject invention to provide an improved augmented glenoid component.
It is a further object of the subject invention to provide a new and useful method of securing an augmented glenoid component to a glenoid surface of a scapula.
It is also an object of the subject invention to provide an improved method of securing an augmented glenoid component to a glenoid surface of a scapula.
It is yet another object of the subject invention to provide an augmented glenoid component and method of securing the same to a glenoid surface of a scapula that is less susceptible to post-operative loosening relative to heretofore designed glenoid components and methods of implanting the same.
The above and other objects, features, and advantages of the subject invention will become apparent from the following description and the attached drawings.